1. Field of the Invention
The present invention relates to a radar apparatus in which the direction of the antenna is recognizable from outside. More particularly, the present invention relates to a radar apparatus in which the direction of the antenna is recognizable from outside, is capable of easily adjusting the direction of the antenna to the vehicle axis even when the antenna face is covered with a protective member and cannot be seen from outside.
2. Description of the Related Art
In order to prevent the occurrence of a traffic accident in which a vehicle running ahead and one running behind crash into each other, a system for indicating the distance between two vehicles has been recently put into practical use. A radar apparatus to be mounted on a vehicle has been developed so that it can be used as a range finder to determine the distance between two vehicles which is used for a warning system. The measuring accuracy of the radar apparatus to be mounted on a vehicle must be high. Therefore, an axis perpendicular to the antenna face, which determines an electric wave irradiating face of the antenna of the radar apparatus, must be accurately adjusted to the central axis (vehicle axis) of the vehicle which is the running direction of the vehicle. This perpendicular axis perpendicular to the antenna face, that is, the central axis of the electric waves transmitted from or received by the antenna will be referred to as an antenna axis, in this specification, hereinafter.
In order to make the antenna axis agree with the vehicle axis when the radar apparatus is attached to a vehicle, it is common to adopt a method in which an irradiating angle of electric waves emitted from the radar apparatus is measured and the thus measured irradiating angle is adjusted so that it becomes parallel with the vehicle axis. According to this method, when the antenna face is mechanically adjusted so that it becomes perpendicular to the vehicle axis, the adjusting time to adjust the antenna axis can be reduced. For example, according to Japanese Unexamined Patent Publication No. 11-326495, after the radar apparatus is mounted on a vehicle, while the antenna face is being exposed or the antenna face is being correlated with an attaching position of the cover face, an inclination of the antenna is measured, and an axis adjusting bolt of the bracket for adjusting the antenna axis is adjusted so that the antenna axis becomes parallel with the vehicle axis which has already been measured.
However, the following problems may be encountered in the conventional antenna axis adjusting method disclosed in Japanese Unexamined Patent Publication No. 11-326495.
(1) In the case where the antenna or the inside of the radar apparatus is exposed, there is a possibility that the radar apparatus is damaged when the radar apparatus is mounted on a vehicle before measurement. Further, in order to prevent the radar apparatus from being damaged, it is necessary to provide a protective cover, which increases the time and labor in the manufacturing process of the radar apparatus.
(2) The antenna cover of the radar apparatus is provided for not only the protection of the inside but also the function of air-tightness. Therefore, when the method is adopted in which the cover is detached and the antenna axis is adjusted, it is difficult to guarantee the air-tightness of the radar apparatus as a product when the cover is attached after the antenna axis has been adjusted.
(3) When the method is adopted in which an inclination of the antenna face is measured while the antenna face is being correlated to the attaching position of the cover face, from the viewpoint of reducing the manufacturing cost and enhancing the productivity, it is difficult to assemble the radar apparatus to a vehicle so that the antenna face can be correlated to the attaching position of the cover face.
The present invention has been accomplished to solve the above problems caused in the antenna axis adjusting method of the conventional radar apparatus. It is an object of the present invention to provide a radar apparatus in which the direction of the antenna is recognizable from outside characterized in that even when the antenna face is covered with a cover so that it is shut off from outside, the direction of the antenna can be recognized from outside and the antenna axis and the vehicle axis can be easily made to agree with each other.
According to the present invention, in the case of mounting the radar apparatus on a vehicle which is covered with a cover in the assembling process so that it is impossible to determine the direction of the antenna axis from outside, a correlative positional relation between the antenna axis and one portion of the chassis of the radar apparatus, or a correlative positional relation between the antenna axis and one portion of the bracket, to which the radar apparatus is attached, has already been detected in the assembling process, and it is possible to know this correlative positional relation from outside. Accordingly, even when a worker cannot see the antenna face because it is covered with a cover in the case of mounting the radar apparatus on the vehicle, it is easy for the worker to adjust the antenna axis to the vehicle axis.
To explain briefly, the present invention provides a radar apparatus in which the direction of the antenna is recognizable from outside comprising: a chassis having a space therein in which at least an antenna is accommodated; an antenna incorporated to the chassis; and a cover which covers the antenna and is attached to the chassis, wherein a correlative positional relation between the antenna axis of the antenna and one portion of the chassis is measured before the chassis is covered with a cover, and the measured value is printed on a seal and the seal is stuck on the radar apparatus. Alternatively, the measured value is stored in the internal memory, and even when the antenna can not be seen from outside because the chassis is covered with the cover, it is possible to recognize the measured value from outside of the radar apparatus, that is, a state of the antenna axis to one portion of the chassis can be confirmed from outside.
In the case where the radar apparatus is mounted on a vehicle by using a bracket, before the chassis is covered with the cover, at least one of the measured values of the correlative positional relation between the antenna and one portion of the chassis, the correlative positional relation between the antenna axis and one portion of the bracket and the correlative positional relation between one portion of the chassis and one portion of the bracket is measured, and this measured value is printed on a seal and the seal is stuck to the radar apparatus or stored in the internal memory, and even when the antenna can not be seen from outside because the chassis is covered with the cover, it is possible to recognize the measured value from outside of the radar apparatus, that is, a state of the antenna axis to one portion of the bracket or a state of the antenna axis to one portion of the chassis, can be confirmed from outside.
of course, a correlative positional relation between the antenna axis and one portion of the chassis, a correlative positional relation between the antenna axis and one portion of the bracket and a correlative positional relation between one portion of the chassis and one portion of the bracket can be measured by various methods.
In the case where the radar apparatus of the present invention is mounted on a vehicle, the vehicle axis of the vehicle is previously measured and, with respect to this vehicle axis, while the antenna axis is being adjusted so that it becomes parallel with the vehicle axis according to any of the measured values of the correlative positional relation between the antenna axis and one portion of the chassis, the correlative positional relation between the antenna axis and one portion of the bracket and the correlative positional relation between one portion of the chassis and one portion of the bracket, the radar apparatus may be mounted on the vehicle.